I've been told by some that the 45 ACP is inherently more accurate than the 9mm cartridge
The straight walled .45acp case & the slower bullet & lower operating pressure of the .45acp sure are a lot easier for me to get a very accurate load w/out any trouble at all.
I gave up trying to get a functional & accurate 124 gr lead bullet load for the tapered case 9mm Luger in frustration...
I'm not a believer in "inherent accuracy".
However - I do believe that some calibers & along with it, the guns they are chambered for, are designed more with function in mind than accuracy.
The 9mm Luger - in the right gun - can shoot laser beam straight - and - with a healthy velocity it has a nice flat trajectory for extended ranges.
That comes with a hefty price tag though as witnessed by the Sig 210 and the H&K P7.
Re: handloading - The .45acp has been a true target shooter's (Bullseye) choice for a good number of years - just like the .38spl.
There's a wealth of data floating around for top shelf accurate loadings.
OTOH - a dozen years ago or so when I gave up on my quest for the 124 gr. 9mm Luger load, I found the info lacking.
I may have to revist that quest once again since it's been a long time & there's bound to be more info to work with.
But - I'm still sort of saddled with two Hi Powers and a CZ75b in 9mm Luger to work with.
While I love all three - tack drivers they ain't.....they do work 100% all the time though...